US2510110A - Step-motor rocket projectile - Google Patents

Description

June 6, 1950 c. N. HICKMAN STEP-MOTOR ROCKET PROJECTILE 4 Sheets-Sheet 1 Filed March 50, 1945 Jvvue/rvfo n ELARIENEEN HIEKMAN,

aammwflm WW4 C. N. HICKMAN STEP-MOTOR ROCKET PROJECTILE June 6, 1950 4 Sheets-Sheet 2 Filed March 30, 1945 jwumvtom ELARENEEN HI EKMAN ac mbwmm June 6, 1950 c. N. HICKMAN STEP-MOTOR ROCKET PROJECTILE 4 Sheets-Sheet 3 Filed March 50, 1945 ELARJENE'EN HICKMAN) Meme/I44 June 6, 1950 c. N. HICKMAN 2,510,110

STEP-MOTOR ROCKET PROJECTILE Filed March 30, 1945 4 Sheets-Sheet 4 E" 5 lEJ I: LAP? ENEEN H [:KMAN,

i atenteci June 6, 1956 (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to improvements in the rocket propulsion of projectiles or other bodies, and more particularly to a step-motor rocket in which the rocket motor has one or more annular series of nozzles or venturi at points along the length of the motor, at which point or points the diameter of the motor reduces in size.

In rockets of conventional design, the density of loading, and hence the performance, is limited by the necessity of providing an adequate port area of jets or nozzles to carry the flow of propellant gases.

It is therefore a primary aim of this invention to provide a step-motor rocket to overcome this limitation by providing the propellent gases with an opportunity to escape through multiple jets or nozzles which are circumferentially arranged and which may be spaced at various points along the length of the rocket motor.

Other objects of this invention are: to provide a rocket projectile construction which permits a high density of loading to attain a relativel high flight velocity and increased range; to provide a rocket-motorconstruction fabricated from a plurality of tubular sections of decreasing diameters which are overlapped to provide a plurality of axially spaced peripheral nozzles or venturi jets; to provide efficient nozzle or jet devices for securing the tubular step-motor rocket sections to one another; to provide a step-motor rocket having nozzles or jets which cause the rocket to be rotated at moderate speeds during launching; to provide a step-motor rocket projectile which when fabricated with an outside diameter of approximately four and one-half inches will be capable of carrying at least ten pounds of high explosive at velocities of the order of 1100 to 1300 feet per second.

Other objects and advantages of the invention will be readily apparent from the following description of the specific embodiments thereof illustrated in the accompanying drawings in which:

Figure 1 is a side elevational view of the step motor rocket;

Figures 2 and 3 are enlarged longitudinal sectional views taken substantially along the planes ofthe lines 22 and 33, respectively, of Figure 1;

'Figure 4 is an end view in elevation looking toward the trailing end of the rocket;

Figure 5 is a cross sectional view of the rocket taken substantially along a plane as indicated by the line 55 of Figure 2;

Figure 6- is a cross sectional view of the rocket taken substantially along a plane as indicated by the line 6-6 of Figure 3;

Figure '7 is a longitudinal sectional view of one of the connecting elements taken substantially along a plane as indicated by the line I---! of Figure 2;

Figure 8 is a view similar to Figure '7 showing a modified position of the connection element;

Figure 9 is a fragmentary side elevational view, partly in section, of the forward end of 'a modified construction of the rocket;

Figure 10 is a view, similar to Figure 9, of the rear end of the modified rocket;

Figure 11 is a cross sectional view of the rocket shown in Figure 9 and taken substantially along a plane aS indicated by the line I |--I I of Figure 9;

Figure 12 is an enlarged cross sectional View of the motor chamber taken substantially along a plane as indicated by the line l2l2 of Figure 10;

Figure 13 is a fragmentary circumferential sectional view of a modified form of connecting means;

Figure 14 is a sectional view of the modified connecting means taken substantially along 'a plane as indicated by the line I l-I4 of Figure 13; and

Figure 15 is a fragmentary circumferential sectional view of another form of connecting means.

Referring more particularly to the drawings,

wherein like reference characters designate like or corresponding parts throughout the several views, I2 designates generally the step motor rocket, shown in Figures 1 to 8 in its entirety, and which includes a head I3, a forward motor chamber M, an intermediate motor chamber I5 and a rear motor chamber [6.

As best seen in Figure 2 the head 13 is recessed to form a burster chamber 11 containing a charge I8 of high explosive. The forward end of the head i3 is open and internally threaded to receive and threadedly engage the neck of a detachable rocket nose [9 to which is connected a booster charge 20 which is disposed in a cavity of the charge Hi. The rear end of the head I3 is reduced and threaded to form a neck 2| to which is threadedly connected the forward end of the cylindrical casing 22 of the forward motor chamber l4. The neck 2| is provided with a central opening 23 in which is mounted the forward, open end of a burster tube 24, which extends rearwardly through a substantial portion of the motor chamber l4 and which is closed at its rear end. The burster tube 24 opens into the burster chamber I! and is likewise filled with the explosive charge 18. The forward end of the burster tube 24 may be secured in any manner in the opening 23, as Joy means of a bonding element 25.

The motor chamber I4 contains a plurality vof sticks or grains of propelling powder 26 which are mounted around the burster tube 24 on a powder trap, designated generally 21'. The powder trap 27 includes an internally threaded collar 28 which threadedly engages arestrioted enter;- nally threaded portion 29 of the neck 2l, for med by the annular recess 39, in neck 2|, which opens rearwardly of said neck into the motor chamber l4 and which is disposed around the opening 23 thereof. The collar 28 .;is provided with a plurality of radially disposed outwardly opening notches or slot's 3l each of which is adapted to receive an end portion of a supporting'rod 32, which rods are provided with heads 33 a't'each end thereof. Each of the rods '32 has one of its heads 33 disposed in the recess 39' and abutting against the forward face of collar 28 to detachably conhe ct the forward ends of the rods 32 to the .Sl pporting collar 28. The rods 32 support a pair of rings 34 and 35 attheir rear ends which form abutments for the rear powder sticks 26 and which are held in place by the heads 33, at the rear ends of the rods 3 2. The rings 34 are provided with outwardly opening radial notches 36 and the rings 35 are provided with inwardly opening radial'notches iil, for detachably mounting said rings on the rods 32. At one or more points intermediate of their ends, rods'32 are provided with enlargements 38, forming stops for additional sets of rings 34 and 35, one of which is disposed on'either side of said enlargements 38, and which combined therewith to form spacing means for the powder sticks 26 carried by each of the rods 32. The trap 21 is adapted to beas- Sfim-bled With U powder sticks 26 thereon and thereafter attached to the neck 21 before the motor casing 22 is applied. It will be noted that as collar 28 is screwed onto threaded portion 29 the heads 33 .Of rods 32 are engagedand carnrned radially inwardly by the outer frusto-conical surface of r'ecess' 30 whereby the forward endsfo'f. all rods are positively held against radial displacement out of their :slotsf3l.

" The motor casing 22 is of the same diameter as the head l3 and is a greater diameter than'the d'asing 39 of the intermediate motor chamber l5. As best seen in Figure 2, the forward end of the motor casing 39 extendsinto the rear end of the motor casing 22 and isdisposed concentric thereto and held thus positioned by means of a plurality of spacing elements 49 which are disposed between the telescoped ends of the casings 22 and 39 and which are fastened thereto by means of rivets or similar faste'nings 4|, which extend through the overlapped casing portions and through the spacing'elements 40. As best seen in Figure '7, the spacing elements 49 are rounded at their forward ends and are provided with elongated tapered rear portions, for. the purpose hereinafter to become. apparent. The intermer diate motor chamber I5 is provided with a powder trap, designated generally '42, for supporting "a. plurality of additional powder sticks 26. The powder trap 4,2v includes a supporting ring 43, as bestseen in Figure 6; which is suitablysecured,

as by welding, to a plurality of circumferentially spaced inwardly projecting studs 44' in the motor chamber l5 and intermediate the ends thereof. The ring 43 is provided with a plurality of circumferentially spaced outwardly opening radial slots or notches adapted to receive a plurality of additional rods 32 which alternately extend rearwardly and forwardly therefrom forsupporting the powder sticks 26, which are held in engagement with the ring 43 by their heads 33. The opposite ends of the rods 32, as seen in Fig- . ures 2 and 3, support sets of rings 34 and 35 in the same manner .as the rods 32 of the trap 21; and the rods of the trap 42 are also provided with enlargements 38 (Figure 2) which function with casing 39,. The motor casing 45 is substantially smauer in diamet r than t e mot r cas n 35 and its forward end is connected to and rnqunted within the re ar end of the casing 39 by spacing elements 40 and rivets (ii, in the same manner a casing 39 is q hect d t the m tor casin 22. The motor casing ,46 contains a plurality of powder sticks '26 which are supported on a pow- .der trap, desi ated ene a ly 5. which co resp ds to the powder trap 21, exc pt thatit i supported at its rear end instead of its fprward end, and by a supporting ring 48 instead of the collar 28. "The ring 53 is provided With aplurality 1 a ia l utwar ly o ning slo .9 for receiving the rear end portions of rods 32 and sa d rin is suitab .seeu ed. as by e d a ai t an nwardly exte d n sh e der .50 9 the mot c n 4.6- t will be uh' e toe at ran Hand 41 are likewiseadapted o be m un ed in h motor ca in s 3. and respe ivel he a s i tor. casin s a e connec ed t form a ert of the rocket I2.

M to asin i5 s m ded w th an interna threaded open rear end 5| which is threadedly neaeed'bye lu 52. which i rec sed at its inner end and prolvided with an integral spider 53 in said recessed inner end. The plug 52 is pre vided w th an o n 54, xtending h rethreueh a d, hihe nto the recessed inner end here-Qi- O n s efih d' v f st c nical en 1. 9::- tions which converge towardpne another to form a restricted intermediate portion. A valve which is elongated andwhich is tapered from in m ate of its end in b th directio length.- wise thereof. to form suhstantially frustoecoliioal end ortions ha on 2 5 id end e o s eated n e m te n 9f the ni .4 o n ma ly closing said opening. A' shear pin 53 extends through a longitudinal bore 5,! in the valve 55 and has a threaded inner end which engages a threaded opening '58 in the spider 53, for retaining the valve 55., under ordinary conditions. in a closed position, as seen in Figure 3. A tail n assembly de at d, en all includes a hub 60, a plurality of radial vanes 6| anda, rim 62. 'Thehub 69 engages around the rear endoi h m or F d n 5 an 1? P i e 4"- t e end with an inturned flange 63 which is clamped between the rear end of the casing lfi and ann r o lde i h ni e 5 r eta he tail fin assembly 5.9 in position on the motorsec.- tion It. The rim 62 which encompasses and is disposed concentric to the hub 60, is connected thereto by thefradial 61; which, are each secured to the hub and rim in any suitable manner, as by welding. The plug 52 seats a plurality of pins 64 which project rearwardly therefrom and which are disposed to guide the valve 55 in its rearward movement, as .will hereinafter be explained. As seen in Figure 4, the plug 52 is provided with a pair of openings 65 which extend lengthwise therethrough to receive lead wires, not shown, extending from a conventional electric igniter, not shown, disposed in one or more of the motor sections and which are adapted to be connected to a conventional firing circuit and source of electric current, not shown, disposed externally of the rocket l2.

From the foregoing, it will be obvious that when the powder sticks 26 of the motor chambers l4, I and 16 are ignited by the aforementioned igniter, the rocket 12 will be launched in a conventional manner. The exterior diameter of the tail fin assembly 59 is equal to that of the head l3 and the forward motor section l4, so that said parts will cooperate to guide the rocket l2 during launching from a tube or rails, not shown. Instead of the propelling gases, produced by the propellants 26, being released through a nozzle at the rear end of the motor chamber, as is conventional in rocket projectiles, the propelling gases from the three motor sections l4, l5 and I6 are normally emitted through the nozzles or jets, formed by the overlapped ends of the motor casings and the spacing elements 40, which nozzles or jets designated 66, are clearly illustrated in Figure 12. The jets, formed by the motor casings 22 and 39, accommodate the gases from the motor section it and the forward half of the motor section l5, and the jets formed by the motor casings 39 and 46 accommodate the propelling gases from the rear half of motor section 15 and the entire rear motor section I6 to thereby distribute the discharge of the gases substantially equally throughout the length of the motor chamber, to prevent a building up of an excess gas pressure at the rear end of the motor chamber, relatively to the forward end. The shape of the spacing elements 40 combined with the overlapping motor section portions to form the jets 66 which are so shaped as to form venturi. It will be readily apparent that the present construction of motor chamber permits the use of a greatly increased amount of propellant, due to the increased discharge capacity of the chamber, so that the range, velocity and payload of the rocket can be substantially increased. By merely canting the spacing elements 40, as illustrated in Figure 8, instead of having said elements disposed lengthwise of the rocket, the venturi 66 will be canted uniformly to cause rotation of the rocket in flight to increase its stabilityand accuracy.

Should an excess pressure build up in the rear motor section l6, the excess pressure thus produced, rather than rupturing said motor section, will shear theenlarged rear end of the shear pin 56 to thereby permit a rearward movement of the valve 55, on the pin 56 and guided by the pins 64 to unseal the opening 54 which, due to its shape, will then function as an additional venturi at the trailing end of the rocket l2 to release this additional gas pressure and to function in the same manner as the single venturi of conventional rockets.

Figures 9, 10 and 11 illustrate a slight modification of the rocket previously described, and disclose a rocket, designated generally 61, of a construction which is intended for use with rockets '6 of larger sizes such as the 7.2 inch and the "10 inch rocket. The rocket 61 includes a head 68, a forward motor section 69, an intermediate motor section 16 and a rear motor section H. The head 68 differs from the head l3 in that the entire charge of high explosive is contained within the chamber of the head and the burster tube of the rocket I2 is dispensed with in order to provide additional motor ichamber area for the rocket propellant. Another construction of trap is provided for the rocket 67 to take care of the increased propellant utilized and, as shown in Figure 9, the trap I2 of the forward motor section 69, includes a forward anchor plate or disk 13 which is suitably secured in any manner to the casing of the motor section 69 and which-is spaced from the rear end of the head 68 by a gasket 14. A plurality of trap rods I5 have their forward ends anchored in the disk 13 and project rearwardly therefrom. Said trap rods are arranged in concentric rings, as best illustrated in Figure 11. The trap rods 15, at a plurality of corresponding positions throughout their lengths and at their rear ends, are provided with enlargements 16 for mounting retaining rings 11 on the rods 15. The retaining rings H are substantially semicircular or channel shaped in cross section, as seen in Figure 9, and are provided with transverse slots 78 extending substantially half way therethrough for receiving the rods 15, for detachably mounting the ring members 11 thereon. Ring members 11 form retaining means for the rear end of the trap 12 and the spacing means, at a plurality of points throughout the length of the trap, for spacing the individual powder sticks or grains [9, which are mounted on the rods 75. One set of enlargements [6 also function for spacing the forward powder sticks 19 from the anchor disk 53. The intermediate motor chamber H1 is provided with a slightly different powder trap construction, designated generally 86. The difference being characterized principall by the fact that due to the reduced diameter of the motor section ID, as compared to the motor section 69, the number of concentric rings of powder sticks 19 which can be employed, is reduced. The only other difference in the powder trap 86 over the powder'trap 12 is that an annular anchoring collar BI is substituted for the anchor disk 13 and is provided with a flange 82 which seats against the forward end of the casing of the motor section 16. The collar BI is likewise secured in any suitable manner to the forward end of the casing of the motor section 10 and has the forward ends of the rods 15 of the trap 86 anchored therein for providing a support for trap 86. The central opening 83 of the collar 8| provides a communicating passage between the motor sections 69 and 10. The rear motor section II is provided with a powder trap 84, mounted in the same manner and constructed in the same way as the powder trap 80, and differing therefrom only in that it contains fewer, and in the present disclosure of the invention, by a single ring of powder sticks 79.

The casings of the motor chambers 69, I0 and 'H are connected together in the same manner as the motor sections of the rocket 12 by the spacing elements 40 and rivets 4| to form the venturi 66.

The rear end of the rocket 61 differs slightly from that of the rocket l2 in that the plug 52 and its associated parts are replaced by a venturi 85 having a threaded neck 86 which engages the internally; threaded rear end 8'| of the casing differs from thetail tir'i assembly 59 'onl y in that *the 'fins thereof are riveted toithe "hub and rim.

The operation 'O'f tlie rocket 6''! is substantially the same as that of the rocket IZfand as previously described, except that it will be readily "apparent that theinc'reased motor chamberarea pr'ovided by'th'e increased diameter of the'rocket ip'lusthe increased area affor'ded by the omission of the :burster "tube, 'p'e'rmits the accommodation :of a substantiall increased quantity of :pro- Lpellants "to thus materially increase the range, velocity and payload capacity "of the rocket 61. The tail 'fin assembly Q6 functions in the same malnner as the tailifin 59, innot-only guiding the rocket in night :but' in guiding it, inconjunction with the 'head and forward motor chamber, in ilaun ching. As in the rocket 12, the spacing elements '40 may be uniformly canted to cant the ve'nturi 66 to thereby produce 'a rotation or the rocket in flight. The blowout disk '89 will be rupturedin case a'nex'ces's press'is built upinthe rear motor chamber I I to "open the venturi 5, "which will then function in the same manner as a "conventional venturi'ofa rocket, for'dise'harg- 'ing the excess propelling gases.

While "both the rockets i| 2 and t! have been illustrated and described as provided with a motor chamber composed of three motor :sec- *ti'ons of :d'ifierent diameters, his 'to be un'derstood that it c'ontemplated 130 construct rockets in accordance with the invention having motor ichambcrs composed of two motor :se'ctions or "four or more motor sections without in any way varying the construction as heretofore de- 's'cr ibed and illustrated "in the drawings.

In lieu of the spacing elements 45, an integral or otherwise suitably cnstructed:spacing rn'em- 'ber, designated generally 9i :and illustrated in Figures 13 and 514;, may be substituted for :the lmembers w. The-spacing member 9! comprises 'a collar or ring having openings 92 formed therein and transversely of the circumference thereof which are shaped to define =venturi of the same shape as the venturi '66 and which form i001).- -:necting "portions 93 therebetween of the same :shape as :the :spacing elements "'40, as clearly iillustr'aited in "Figure 14. The spacing emembers :9I are made of the correct interior and exterior diameters andradial thickness to fit snugly into the annular space formed between theiconcentric overlaplping portions of adjacent motor section .7

casings and are -adafpted to be secured therein in tany suitablemanner as'b'y welding crr by'means of :fastenings, such .as the rivets M which .Will :extendithroug'h the-portions '93 In Figure 15 a, slightly modified f'ormbflsp'acling-member, designated generally 94, is "disclosed. l'lhe spacing member -94 differs from the spacrn'g member f in that the 'venturi 95 thereof in addition to opening outwardly of the "radial sides of the member 34 also open outwardly of the circumference thereof and the :outer wall of the jets 'or venturi 95 are defined by the "surrounding portion of the -casing, indicated in Figwe 'by the reference numeral 96, which 'encompasses the member 94. The venturi 95 'for-m the radial portions 91, which correspond to the portions 93, and the member is mounted in the same manner and functions in the same Way 'as the member '91. Obviously, if desired, the militari y: and -85 could be canted to menace -*Various other modiiicadaions and changes in addition to those herein shown and described are"con'tem-pl'ated and ma-yobviously *be resorted 130," without departing from the spirit and-"scope or the invention as hereinafter defined by t-he appended claims, wherein only *the preferred embodiments 0f the invention have -'beendi-sclosed.

1. A step-motor *roket comprising a head, three tubular motor secti0ns *ali-ned with said head, said sectiohsbeing "of -'diiferent diameters with thedarge'st diameter section *se'cix'redto the head and with the smallest "diameter section forming the -stern "end ofthe rocket, *rearwar'dly "directed *noz'zles be'tween said motor'section's, and a *cage type *pow'dertrap secured in each "of "said sections, the trap in said forward section being supported iromit's -forwardend, *the trap in "said stern "section being supported from its stern end. f2. A-step m-otor rocket "comprising a head, three tabular "motor sections 'alin'ed with "said "head, said"sections being or different diameters "with the largest-diameter section secured to said head and with the smallest "diameter section forming the stern o'f'the rocket, rearwardly 'tlirecited n'oz z'les between said 'inctor "sections, a normally closed pressure relief valve in therear "end portion of said tsmallest diametered motor section, and means "holding said'relief valve in closed fpositi'onysaid la's--named means being she-arable in "responseto a predetermined presenre in said rear end portion to thereby open said valve.

ia-step=motor rocket comprising first, second and third hollow cylindrical motor "chambers of progressively "smaller diameters, means "forming Vnturi passagesand securing the forward ends of sai'dfsecon'd and th'rrd'chambers within and in overlapping relation with the rear ends of said-first andsecond motor chambers respectively, a powder trap fixedly carried by and Withineach 'saidchamber, there b-einga gas discharge passageway through the rear end Of"Saiii third chamber, means closing said passageway but "operable -tb'open-tlre same in'respon'se to a-pre- -determined gas pre'ssorewithi-n said third'cha'rnher.

afilfn'a rocket, a hollow cylindrical motor chamber, "a hollow, explosive-containing head secured in and-closing the "forward end of said chamber, "a collar having circulnierentially "s aced 'apeftmes and rigidly engaged with the fport'i'ono'f said headwvithinsaid chamber, 13, .pluralityo'f trap rods "each having one end fixed :in a "respective aperture, and means uniting the other ends 7 of .said rods to maintainall said 'ro'ds fin substantially Tparallel relation, said lastnamed means comprising first and second adjacent coaxial rings, said first ring having "radial slots extending inwardly from "the outer periph- 'er'y'there'of, said's'e'condring having radial sl'ots extending outwardly from 'the inner periphery thereof, "each said rod passing through a radial "slot 'iire ach'said ring.

5. 'In a rocket, a hollow cylindrical motor Tha'mber, "a powder trap in "said chamber in-- "cluding a -plurality of ci'rcumferen'tially-spaced parallel trap rods on each of which a powder grain is strung, first and second adjacent coaxial rings in said chamber, said first ring having 'a plurality of radial slots extending inward- 1y from'the outer periphery thereof, said-second ring having a plurality of radial slots extending outwardly from the inner periphery thereof, each slot of one ring coinciding with and overlapping, by the diametral dimension of said rods, a corresponding slot of the other ring, when said rings are coaxial, each said rod passing through a pair of coinciding slots, whereby all rods are held in fixed relation, and means carried by each rod to prevent axial movement of each ring in one direction therealong.

CLARENCE N. HICKMAN.

REFERENCE S CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,402,809 Farr June 25, 1946 FOREIGN PATENTS Number Country Date 11,705 France Oct. 5, 1844 73,840 Germany Mar. 9, 1894 831,496 France June 7, 1932 375,260 Italy Sept. 29, 1939 516,865 Great Britain Jan. 12, 1940

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